This invention relates to a lap-joint between two plastic sheets and more particularly but not by way of limitation to a pair of thermoplastic laminate ply sheets joined together by a multiple lap-joint.
Heretofore, attempts have been made at obtaining stronger bonded joints, by joining together thermoplastic laminate sheets using improved adhesive, the design of which was found to be expensive and time-consuming. Further, different joint geometries such as double-lap joints, scarf joints and reinforced butt joints were used to increase joint strength, but required either more material in the joint area or machining of the joint area. More material resulted in higher joint weight and machining was found to be undesirable and expensive.
In U.S. Pat. No. 3,046,181 to Mann et al, U.S. Pat. No. 3,300,826 to Read, U.S. Pat. No. 3,388,020 to Gates, U.S. Pat. No. 3,619,314 to Ecureus, U.S. Pat. No. 3,985,169 to Chow, U.S. Pat. No. 4,279,676 to Morrison et al and U.S. Pat. No. 4,366,014 to Pollard various types of laminates are shown using different means of joining together adjacent sheets of thermoplastic. Also, some of the above mentioned patents disclose different types of joining together wood products. None of these prior art patents specifically disclose the unique features of a multiple lap-joint and method of making the lap-joint as described herein.